Shelf



FIG. 1 is a perspective view of a shelf showing our new design;

FIG. 2 is an end elevation view of the right end of the shelf, the left end appearing identical;

FIG. 3 is a top plan view of the shelf;

FIG. 4 is a front elevation view of the shelf; and,

FIG. 5 is a bottom plan view of the shelf. 

The ornamental design for a shelf, as shown and described. 